body.html{
  margin: 0;
  padding: 0;
}
#main{
  margin: 50px auto;
  width: 260px;
}
#calc{
  margin-left: 52px;
  width:60px;
}
input{
  margin: 5px 0;
}

#width-validate, #height-validate {
  color: red;
  margin-left: 52px;
}

input:valid+span:after {
  content: '√';
  color: green;
}

input:invalid+span:after {
  content: '×';
  color: red;
}
